Toggle breech block locking means for a gas piston operated gun



Aug. 25, 1959 N. NOMAR TOGGLE BREECH BLOCK LOCKING MEANS FOR A GAS PISTON OPERATED GUN 5 Sheets-Sheet 1 Filed Oct. 4, 1955 INVENTOR.

LOUIS N. NOMAR wig-W Aug. 25, 1959 L. N. NOMAR TOGGLE BREECH BLOCK LOCKING MEANS FOR A GAS PISTON OPERATED GUN 5 Sheets-Sheet 2 Filed Oct. 4, 1955 INVENTOR.

LOUIS N.NOMAR x w mww wyaw m wI ATTORNEY Aug. 25, 1959 N. NOMAR TOGGLE BREECH BLOCK LOCKING MEANS FOR A GAS PISTON OPERATED GUN 5 Sheets-Sheeti Filed Oct. 4. 1955 INVENTOR.

LOUIS N. NOMAR ATTORNEY Aug. 25, 1959 L. N. NOMAR TOGGLE BREECH BLOCK LOCKING MEANS FOR A GAS PISTON OPERATED GUN 5 Sheets-Sheet 4 Filed Oct. 4, 1955 INVENTOR.

LOUIS N. NOMAR ATTORNEY 5 Sheets-Sheet 5 FIG. 2|.

FIG. 22.

L. N. NOMAR TOGGLE BREECH BLOCK LOCKING MEANS FOR A GAS PISTON OPERATED GUN FIG. IS.

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FIG.

Aug. 25, 1959 Filed Oct. 4. 1955 O 2 M F \k m m l. ii

INVENTOR.

LOUIS N. NOMAR ATTORNEY 2,900,878 Patented Aug. 25, 1959 TOGGLE BREECH BLOCK LOCKING MEANS FOR A GAS PISTON OPERATED GUN Louis Nolan Nomar, Charleston, W. Va., assignor to Nomar Arms, Inc., Charleston, W. Va., a corporation of West Virginia Application October 4, 1955, Serial No. 538,340

2 Claims. (Cl. 89-189) This is a continuation-in-part of my application for patent Ser. No. 284,159, filed April 24, 1952, now abancloned.

This invention relates to firearms and is more particularly concerned with machine gun type of firearms.

The general object of the invention is the provision of a machine gun which has novel features and improved operating characteristics over that of previously known guns, a particularly important feature being a sharp reduction in recoil, improved accuracy, selective action as between automatic firing and single shot or semi-automatic firing, and rapid firing characteristics.

A specific object of the invention is the provision of a gun of the type mentioned having improved means for ejecting the empty shells.

Other specific objects of the invention are the provision of an improved breech mechanism; an improved firing pin and operating means therefor; and an improved selector means whereby a single means is provided for adjusting the firing to automatic, single shot, or putting the gun on safety.

A further object is the provision of safety means which will stop the automatic operation of the firearm when the last shell has been fired.

A still further object is to provide an automatic gun or rifle which contains the improvements and novel means set forth above and yet is relatively simple in construction, easy to operate, has only a small number of parts, is sturdy, not likely to get out of order, and which will fire automatically at a very rapid rate.

A still further object is to provide a firearm of the type mentioned which is relatively light in weight as compared to similar types of firearms, particularly those now used by the armed forces of the United States of America.

A still further object of the invention is the provision of a firearm of the type mentioned, the operation of which involves substantially no jarring or heavy kicking or raising of the muzzle when fired.

These and other objects and advantages of the invention will appear more fully from the following description considered together with the accompanying drawing.

In the drawing:

Fig. 1 is a longitudinal sectional view, partly broken away, of an embodiment of the invention.

Fig. 2 is a longitudinal section of one of the portions broken away from Fig. 1.

Fig. 3 is a section along the line 3--3 of Fig. 1.

Fig. 4 is a view of a portion of Fig. 1 showing the firing mechanism in dilferent positions.

Fig. 5 is a longitudinal section on an enlarged scale of the gas cylinder and piston therein.

Fig. 6 is a cross-sectional view along the line 6-6 of Fig. 3.

Fig. 7 is a side elevational view of the firing mechanism, apart from the breech chamber.

Fig. 8 is a rear end view of the mechanism of Fig. 7, partly in section.

Fig. 9 is a top plan view of the firing mechanism shown in Fig. 7, partly broken away.

Fig. 10 is a side elevational view of the breech section of the gun.

Figs. 11, 12 and 13 are longitudinal sectional views of the trigger mechanism in different positions.

Fig. 14 is a sectional view along the line 1414 of Fig. 11.

Fig. 15 is a plan sectional view along the line 1515 of Fig. 11.

Fig. 16 is a sectional view along the line 16--16 of Fig. 15.

. Fig. 17 is a top planview of the bottom wall of the breech chamber apart from the gun as a whole.

Fig. 18 is a section along the line 18-18 of Fig. 17.

Fig. 19 is a front end elevational view of the breech block alone.

Fig. 20 is a rear elevational view of the cartridge clip holder, partly in section.

Fig. 21 is a side elevational view of the firing pin push bar or shank.

Fig. 22 is a perspective view of the cartridge extractor.

Fig. 23 is a perspective view of the cartridge ejector.

Fig. 24 is a perspective view of the rear slide block, with portions of the push arms connected thereto.

Referring with more particularity to the drawing in which like numerals designate like parts, the embodiment illustrated comprises a gun, rifle, or other firearm having a barrel 31, a breech section 32 and a stock 33.

The breech end of the barrel 31 is provided with external threads 34 which engage complementary internal threads 35 of a hollow nipple 36 on the forward end of the breech section.

The breech section 32 comprises a hollow breech chamber having side walls 37 and 38, a top wall 39 and a bottom wall 40. This chamber is aligned with the bore 41 of the barrel 31 and it contains a forward or breech slide block 42 and a rearward slide block or firing pin actuator 43. These blocks are connected together by links hereinafter more fully described.

The rearward slide block or actuator 43 has a smooth surface 44 which rests on and slides forwardly and rearwardly on the bottom wall 40. It also has vertical side pieces 45 and 46 which engage the sides of the bottom wall 40 and underlie the bottom edges 47 and 48, respectively, of the side walls 37 and 38.

The breech block 42 is provided with a groove 49 on the left side which engages a key 50 set in a groove 51 on the side wall 37. The key is held in position by means of an outwardly projecting stub pin 52 integral therewith which engages an aperture 53 in the side wall 37.

Projecting forwardly from the rearward slide block 43 is a member 54 pivotally connected to the rearward slide block 43 and which carries an elongated shank or firing pin push bar 55 which slidably engages an aperture 56 longitudinally through the forward or breech block 42, said aperture being axially aligned with the bore 41 of the barrel 31.

The forward end of the aperture 56 has a constricted portion or counterbore 57 for slidably engaging the firing pin 58 which is secured co-axially to and carried by the forward end of the shank 55.

A recessed portion 59 is provided in the forward end of the forward slide block as a seat for the rim of the cartridge.

The two slide blocks 42 and 43 are connected together by means of a pair of links 60 and 61 which together comprise a collapsible linkage. The locking or bracing link 60 is disposed generally horizontal and has a bifurcated forward end 62 which is pivotally connected to a rearwardly projecting lug 63 of the forward or breech block 42 by a pin 64.

to receive therebetween the upper end 66 of the link 61 to which it is pivotally connected by a pin 67'. The lower end of the link 61 is co-pivoted with a rearwardly projecting lobe 54A oftthe niember-54 to the rear slide block 43 by acommonpintle 68, g r V 4 As a result of this linkage between the two slide blocks, they may be moved relative to each other a limited extent. The first or contracted position of these slide blocks is determined by abutment between a boss 69 on theforward end of the member 54 and the-rearward end of the forward or breech block 42. (See Fig. l.) In this position too, the linkage, comprising the links 60 and 61, is in its collapsed position. The second or estendedposition of the two slide blocks is determined by abutment of the link 60 against an upper shoulder 69A of the boss 69. 1 (See Fig. 4.) i In this position the linkage is in its expanded position. I V V V When the slide blocks are in their contracted position, as shown in Fig. l, the link arrangement described causes the rear end of the horizontal link to become elevated. The said horizontal link 'carries lugs or ears 70 which, in the elevated position of the said link, projectsinto' a slot 71 in the roof or top wall 39 of the breech chamber. in

this position, any rearward pressure against the forward end of the breech block 42 is totally inelfective to move said block because the force is transmitted directly to the horizontal link and the ears 70 against the rear edge 72 of the slot 71 constituting a forwardly facing shoulder of the rear top wall of the breech chamber with which the ears are now in contact. The only way in which the forward slide block can be released from this position is by lowering the ears 70 out of the slot 71. This can only be done by moving the slide block 43 rearwardly relative to the forward slide block 42. This is effected by a pair of parallel arms 73 and 74 connected at their rear ends to the side member 45 and 46, respectively, of the rear slide block 43, and slida'bly disposed in channels 73A and 74A of the bottom wall 40.

When the blocks 42 and 43 are in their extended relative positions, the ears 70'underlie the top wall 39 of the breech chamber and contact the inner face 75 thereof to stabilize the blocks as they move in the breech chamber. (See Fig. 4.)

The forward ends of the arms 73 and 74 are connected to a hollow piston rod 76, the forward end of which carries a conical or dome-shaped piston head 77 which is slidably disposed in a hollow cylinder 78. Said cylinder is secured to the lower side of the barrel 31 by a bracket 79 and is communicated with the bore 41 of the barrel 7 by a passageway consisting of an aperture 80 through the wall of the barrel, another aperture 81 through the wall of the cylinder 78,.and an intermediate aperture 82 in the bracket 79. Accordingly, explosion gas passing from the barrel 31 into the cylinder 78 tends to force the piston rearwardly in the cylinder and when it is moved rearwardly, it carries 'with it the piston rod 76 and the arms 73 and 74. a a p The initial length of travel a of the piston head 77 in the cylinder for a fractional part 'of its stroke is made under substantially gas tight conditions between the said head and the cylinder wall. For the remaining length b of the stroke, the inside diameter 78A ofthe cylinder is gradually widened to permit the gas to leak past the piston head'as shown in Fig. 5. This results in an impact thrust by the gas entering the cylinder from the barrel through the passageway at the front of the. cylinder and a dissipation of the gas as the piston head moves rearwardly, thus providing what may be termed a split cycle operation and permitting a more rapid rate of firing.

The forward end of the cylinder 78 is closed by a removable threaded' plug 82A, which-when'removed permits cleaning the cylinder and alsorenders the firearm inoperative, for automatic or semi-automatic. operation' the hollow piston rod 76 bearing at the forward end against the forward inner wall 84 of the said piston rod. The rear portion of the spring 83 is disposed about a guide plunger 85 which carries an enlarged portion 86 at the rearward end to provide a forwardly facing shoulder 87 p for abutting the rear end of the spring 83. The enlarged portion 86 is rearwardly tapered and seated in a socket 88 formed in a downwardly projecting boss 89 of the breech chamber. 7

The bottom wall 40 has an opening 90 in which is mounted the horizontal arm 91 of a bell crank latch 92 as the trigger operated release means. The vertical arm 93 of the bell crank latch passes downwardly between side walls94 and'95 depending from the bottom wall. The bell crank is fulcrurned to the said walls by a pin 96.

The vertical arm 93 has an upwardly facing shoulder 97 which is in contact with the free end of a cantilever leaf spring 98. The said spring 98 at the opposite end underlies the bottom wall 40 and is anchored thereto by a screw 99. a Y

The horizontal arm 91 of the bell crank has a latch portion 100 thereof which projects above the inner surface of the bottom wall under the influence of spring 98 to provide a rearwardly facing shoulder 101 for contacting the forward end 102 of the rear slide block when said block is behind the shoulder. The upper edge 103 of the arm 91 slopes downwardly toward the front from the shoulder 101.

trigger guard 104 is integral with a horizontal trigger mounting plate 105 which underlies and is secured in spaced relation to the bottom wall 40 by means of bolts 106 and 107 in conjunction with spacer cylinders or spools 108 and 109, respectively.

The trigger 110 is pivotally mounted in the guard 104 by a pin 111 passing through the trigger and engaging the side walls 112 and 113 of a cut out portion 114 in the mounting plate 105. The-trigger is biased to a forward position by means of a cantilever leaf spring 115 having its rear end anchored to the mounting plate 105 by a screw 116.and having its free end 117 pressing against an upwardly facing shoulder 118 formed in the trigger to therear of its pivot wis.

'The movement of the trigger forwardly is limited by contact of a forwardly facing shoulder 119 of the trigger below its pivot axis with the forward edges 120 of the cut out portion'114.

The trigger 110 has a lobe 121 projecting upwardly from the pivot axis and it is pin-connected to the rear end of a'horizontal sear 122 by a pintle 123. The forward end of the sear is positioned just behind the lower end of the vertical arm 93 of the bell crank latch 92 and it is adapted to contact the said vertical arm when the sear movesforward as the triggeris pulled rearward, thus rotating the bell crank counterclockwise, resulting in releasing the shoulder 101 from contact with the forward end 102 of the rear slide block.

A leaf spring 124 has" its rear end anchored to the bottom wall 40 by a bolt'125. The forward end of the spring 124 presses downwardly against the top of sear 122 to slidably engage it with'an upwardly and rearwardly projecting support 126 which is integral with a horizontally disposed rocker bar 127. v The bar 127 has a downwardly projecting cylindrical lobe 128 which is rockably set in a corresponding hollow portion 129 of the trigger guard and held. therein by a pin 130. The lobe 128 has a medial cutout portion 131 and the pin has a medial annular recessed portion 132. narrower than the cut out portion 131.

The recessed portion 132 is a bearing for an annular band 133 on the forward end of an abutment member 134 underlying a forwardly projecting lip 135 of the trigger above the trigger pivot pin 111.

The member 134 has three abutment surfaces 136, 137 and 138 at the top, at dilferent elevations. The lip 135 A coil spring 83 has its front portion disposed 75 is no wider than the width of any of these abutment surfaces. Said surfaces are adapted to be selectively aligned with the said lip by lateral movement of the pin 130. When the lower abutment surface 136 is aligned with the lip 135 on one side it permits the trigger to move rearwardly a distance suflicient to carry the sear forward far enough to engage the front side of the support 126, whereupon, upon release of pressure on the trigger, the sear moves backward and causes the bar 127 to revolve counterclockwise on pin 130 until it is released by the change in angularity between the support 126 and the sear, whereupon, the bar 127 returns to its original position.

When the abutment member is moved to the opposite position where the opposite surface 138 is aligned with the lip 135, the movement of the trigger is restricted to prevent the sear from catching on the front side of the support 126 whereupon the bar 127 remains" stationary.

When the abutment member is moved to the intermediate position where the center and uppermost abutment surface 138 is aligned with the lip 135, it blocks movement of the trigger, thereby placing the rifle on safety.

The abutment member is held in any of its lateral positions by means of a hollow pointed slide pin 139 set in a well 140 between the lobe 128 and the support 126 against a spring 141. The point 142 of the pin projects rearwardly and under the influence of the spring 141 contacts a forwardly facing shoulder 143 having notches 144, 145 and 146 for the reception of the point 142. By

.moving the pin 130 laterally, the position of the abutment member 134 can be changed relative to the hp 135 by a disengagement of the pin 139 with one of the notches 144, 145, 146 and a snap engagement with another notch.

A cartridge clip 147 of a conventional design is adapted to be inserted in an opening 148 in the trigger mounting plate 105. The clip 147 is releasably held in operative position by means of a spring pressed latch 149 which is [formed with a locking detent 150 engageable in a keeper opening 151 formed in the adjacent wall of the clip 147.

The clip 147 includes a follower 152 which is constantly urged upwardly by a spring 153. The follower 152 is formed with a rearwardly projecting lug 154 aligned with the forward end of the bar 127 and which, upon emptying of the clip 147, is adapted to contact said bar and elevate it. This action results in a counterclockwise rotation of the sear support 126, whereupon this support is removed from the forward end of the sear 122 and it falls down out of contact with the vertical arm 93 of the bell crank 92. Consequently, when the clip is emptied of cartridges, the trigger is rendered inoperative and the rifle cannot be fired.

The cartridge clip 147 is preferably of the double row staggered type and a pair of diagonal guide grooves 155 and 156 therefor are formed in side by side relation in the breech throat along the bottom wall 40 of the breech chamber. As the uppermost cartridge leaves the cartridge clip 147, it must pass along one of these grooves, nose first, as the breech block 42 moves rearwardly from its firing position. The bottom of the block 42 is provided with a pair of longitudinal recesses 157 and 158, corresponding to the breech throat grooves 155 and 156, respectively. Accordingly, as the breech block moves rearwardly, the cartridge is contacted by one of these grooves which serves to hold the cartridge in longitudinal alignment and prevent jamming.

When the breech slide block 42 retracts beyond the rim end of the cartridge, the cartridge moves into firing position between the barrel bore 41 and the recess 59 of the breech block. When the breech block moves forward from its retracted position, it forces the cartridge into the breech of the barrel and the rim 159 of the cartridge shell 160 becomes seated in the recess 59.

In order to extract the shell 160 after the cartridge is fired, a gripper or extractor is provided in the form of a bowed leaf spring 161 in a groove 162 along side the breech block 42. The forward end of the spring 161 is provided with a latch hook or barb 163 which, as the breech block moves into firing position, grips the rim 159 of the cartridge as shown in Fig. 3. Consequently, after firing, when the breech block is retracted, the barb 163 gripping the shell, carries it back with it On the opposite side of the breech block, the key member 50 is provided with an ejector 164 at the forward end in the shape of an inwardly projecting triangular extension. The ejector 164 slides in a secondary groove 165 in the side wall 166 of the main groove 49 on the breech block and it is aligned with the locus of a portion of the edge of the cartridge shell rim 159. Conse quently, as the breech block retracts and carries with it the spent shell, the shell is contacted by the extractor 164, pivoted laterally around the hook 163 and ejected from the rifle through an opening 167 in the side wall 38 of the breech chamber.

A slide panel 168 is slidably mounted between the inner face of the side wall 38 and the breech block 42. This slide panel is sufficiently long and wide to cover the opening 167 of the breech chamber. It extends rearwardly along the horizontal link 60 and is provided at the rear with a notch 169 which fits over an outwardly projecting portion 170 of the side piece 46 that is connected to the rear slide block 43 and the right push arm 74.

The upper edge of the slide panel 168 rides in a rabbeted edge 171 of the upper edge 172 of the opening 167. The lower edge of the slide panel 168 rests on an inner recessed extension 173 of the lower edge of said opening.

The front end of the slide panel 168 is provided with an outwardly extending knurled knob 174 which is used to manually cock the mechanism.

The cycle of operation is as follows: With the mechanism in the position indicated by the dotted lines of Fig. 4, when the trigger is pulled, the breech mechanism moves forward under the force of the spring 83 acting through the arms 73 and 74 against the rear slide block 43. As the breech mechanism moves forward, the ears or lugs 70 bear against the innerface 75 of the wall 39, thereby causing the forward slide block 42 to move forward also. When the cars 70 reach the slot 71, the forward slide block 42 is in abutting engagement with the shell 160. Continued forward movement of the block 43 causes the firing pin 58 to move forward in the counterbore 57. At the same time the link 61 forces the rearward end of the link 60 upwardly so that the cars 70 enter the slot 71 and move upwardly therein to engage the edge 72 as an abutment. When the firing pin strikes the shell 160, the resulting explosion force reacts rearwardly against the block 42, the link 60, ears 70 and edge 72 as a result of which there is no movement of the block 42, thereby permitting the force of the explosion to act forward fully against the bullet. Gas from the explosion enters the cylinder 78 through the apertures 80 and 82 and exerts a force rearwardly against the piston head 77 and against the action of the spring 83. Since this piston is connected by the arms 73 and 74 to the rear breach block 43, it acts first to lower the ears 70 from the slot 71, and then to move the block 43 together with its associated parts rearwardly to the position shown in the dotted lines of Fig. 4, whereupon the cycle is completed.

Having thus described my invention, I claim:

1. In a firearm, a barrel, members forming in relation to the barrel a breech chamber having a top wall, said wall having a forwardly facing shoulder and a bottom surface extending rearwardly from the shoulder parallel to the longitudinal axis of the chamber, a breech slide block and a firing pin actuator slidably mounted in the chamber, means cooperating with said bottom surface to constrain the movements of the said block and actuator parallel to the longitudinal axis of the chamber, said block being disposed in the chamber forwardly of the actuator, a reciprocating firing pin coaxially aligned with and constrainedyfor coaxial movement relative to the bar rel, said pin being fixed to and movable with the actuator, said block having a longitudinal aperture therethrough slidably engaging the firing pin, said means including a collapsible linkage connecting the said block and actuator, said linkage including a bracing link for the block, said bracing link being adjacent to and slidable in relation to the said bottom surface, said bracing link having a vertically movable part a portion of which is adapted to engage said shoulder when the block and actuator are forwardmost in the breech chamber and the linkage is collapsed, thereby to brace the block against rearward movement under force applied rearwardly tothe block, and means connected to the actuator for moving it rearwardly from its forwardmost position in the breech chamber, thereby to expand the linkage from the collapsed position and disengage the vertically movable part from the shoulder another portion of said movable part engaging said bottom surface when the linkage is expanded.

2. In a firearm, a barrel, members forming in relation to the barrel a breech chamber having a top wall, said wall being formed with a forwardly facing shoulder paral' lel to the longitudinal axis of the chamber, a breech slide blockand a firing pin actuator slidably mounted in the chamber, means cooperating with said wall to constrain the movements of the said block and actuator parallel to the longitudinal axis of the chamber, said block being disposed in the chamber forwardly of the actuator, a reciprocable firing pin coaxially aligned with and constrained for coaxial reciprocation relative to the barrel, said pin being fixed to and movable with the actuator, said block having a longitudinal aperture therethrough slidably engaging the firing pin, said means including a collapsible linkage connecting the said block and actuator, said linkage including a bracing link for the block, said bracing link being adjacent to and slidablein relation to the said bottom surface and comprising upstanding ears vertically movable with a part of the bracing link when the linkage is actuated between its collapsed and expanded positions by the relative movement of the block and actuator, a portion of saidea'rs being adapted in the upper position to abut said shoulder when the block and actuator are intheir 'forwardmost' position in the chamber, thereby to brace the block, and means connected to the actuator for moving it rearwardly from its forwardrnost position in the breech chamber, thereby to expand the linkage from the collapsed position, lower and disengage the said portion of the cars from the shoulder and permit rearward movement ofthe block and act'uator'in the breech chamber, another portion of said ears engaging said bottomsurface during saidlrearward movement.

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Simpson Feb.'2, 1954 

